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How to check your tax assessment in Luxembourg
Income tax statement, décompte, global rate: learn to read your Luxembourg tax assessment, spot an error and react within the right deadlines, with taxx.lu.
You've filed your return. A few weeks later, an envelope from the ACD lands on your doormat. Most people file it away in a drawer without really reading it. Which is a shame, because this is exactly where the amount you'll get back, or pay, is decided.
The tax office handles thousands of files, and a mistake can slip through. Checking your tax assessment is your right. And, above all, it comes with deadlines worth knowing.
What you'll receive
In most cases, you get two documents:
- the income tax statement (bulletin de l'impôt sur le revenu), which sums up your income and tax situation for the year in question;
- the décompte, the statement of account: what you've already paid, and what's left to pay or reclaim.
If you've declared foreign income, a third document joins them: the determination of the global tax rate (détermination du taux d'impôt global).
Want to see what these actually look like? Our help centre breaks down each document, screenshots included.
The décompte: your bottom line
Start here. The décompte is the figure-by-figure summary of your whole assessment. It shows the payments you've already made, then the final result: a refund in your favour, or a balance still due.
Compare that with what you were expecting. If you estimated your tax before filing, say on taxx.lu, you already have a figure in mind. Two numbers close together: all good. A big gap: time to find out why.
The income tax statement: the detail
The statement confirms the data the administration has taken into account. This is where you check the detail: your income, your deductions, your allowances.
Go through each line. Are your business expenses there? Your special expenses, your loan interest, your insurance premiums? A forgotten deduction is money left on the table.
The ACD changed your return? It'll tell you
If the administration departs from what you declared, it will, as a rule, add a note at the bottom of the statement, under the line "L'imposition diffère de la déclaration sur les points suivants" (the assessment differs from the return on the following points). Read it closely: it tells you exactly what changed, and why.
Foreign income: the global tax rate
This third document only concerns taxpayers with foreign income. It works out your effective tax rate by counting all of your income, including income that's exempt in Luxembourg under tax treaties. That rate then applies only to the income taxable here.
How to check, in practice
Four quick habits are enough:
- compare the final result on the décompte with your own estimate;
- check, line by line, that every deduction and allowance has been applied;
- read the ACD's explanatory note if anything differs from your return;
- check your personal and bank details, since the ACD now asks for a RIB (bank account details) for any refund.
Not sure about your assessment? Have it checked
With the Plus, Premium and Platinum packs, if the ACD result differs from the one shown on taxx.lu, our team reviews your tax assessment. If the error is the administration's, it prepares an appeal letter ready to send. A safety net you don't get filing on your own on MyGuichet.
Deadlines you shouldn't miss
Two deadlines matter, and they do different jobs.
To pay a balance due: you've one month from receiving the assessment. After that, late-payment interest can apply.
Pay first, dispute later
Filing a complaint doesn't excuse you from paying the tax due on time. If the complaint goes your way, the overpayment is refunded afterwards. So pay what's due, even if you plan to dispute it.
To request a correction: you've three months from receiving the assessment. A mistake can be settled informally or, if needed, through a formal réclamation (complaint).
That said, filing a complaint by the book and on time isn't everyone's idea of a good afternoon. That's where our team comes in: with the Plus, Premium and Platinum packs, if an administration error is confirmed, it prepares the appeal for you, ready to send. You don't have to decode every step on your own.
It works both ways, too. By flagging a discrepancy, you help us spot the most common errors and improve the tool, for you and for everyone else. And you don't start from scratch each year: your taxx.lu account gives you an overview, year after year.
As for how long the ACD takes to issue the assessment, there's no fixed rule: the administration is legally allowed several years to process a file. So we can't promise you a date.
In short
Getting your tax assessment isn't the end of the road, it's the final check. Read the décompte for the bottom line, the statement for the detail, spot any difference, and keep the three-month complaint window in mind.
And if something's off, you're not on your own to sort it out.
